Exemplary embodiments of the present invention relate to a system and for determining the position of a communication platform. In particular, the present invention relates to position determination using a directed or focused communication connection from one communication platform to another communication platform or between these two communication platforms.
Various methods tier determining a position are currently known, for example a means of locomotion on the ground or in the air space above. The most common absolute position determination method is based on radio frequency satellite signals, for example, the Global Positioning System (GPS) or the similar Galileo and Glonass systems. By the receipt of corresponding signals from at least three satellites and by triangulation using the known absolute satellite positions, the position of the receiver in three-dimensional space can be determined. However, satellite-based location determination methods using RF signals are prone to failure for example, through established near-earth orbit jamming transmitters, which superimpose signals on the RF signals emitted by the satellites making their evaluation difficult or impossible.
Other well-known position determination methods, for example based on a known infrastructure of communication networks, are also available.
Relative position determination methods use, for example, the direction of movement as well as elapsed time, for example, by using a time instrument or a gyroscope or gyro compass in order to determine a relative change in position starting from a known position and direction of movement, and thus calculating an actual position. However, it is common in relative positioning methods that small errors or deviations in the course determination accumulate over time and can lead to an assumed but significantly wrong position.
Exemplary embodiments of the present invention provide a novel position determination that enables absolute positioning that is comparable to satellite-based radio frequency signals, but offers reduced susceptibility to faults.
Accordingly, exemplary embodiments of the present invention are directed to a system for determining the position of a communication platform is disclosed by means of a first communication platform and a second communication platform, and a method for determining the position of a communication platform.
According to an exemplary embodiment of the present invention, a system for determining the position of a communication platform is disclosed that comprises a first communication platform and a second communication platform. In this case, at least the first communication platform is in communication connection with the second communication platform, whereby the communication connection can be embodied as a focusable communication connection. In this way, the direction or orientation of the focusing of the communication connection can be determined. Consequently, this determinable focusing of the communication connection should enable the determination of a position of the second communication platform.
According to another exemplary embodiment of the present invention, a first communication platform is disclosed that can be in communication with a second communication platform. The communication connection may again be formed as a focusable communication connection, from which the direction or orientation of the focusing of the communication connection can be determined.
Consequently, a position of the second communication platform may be determined through this determinable focusing of the communication connection.
According to another exemplary embodiment of the present invention, a second communication platform indicates that it can receive a communication connection from a first communication platform, whereby the communication connection may again be formed as a focusable communication connection. The direction or orientation of the focusing of the communication connection can again be determined, whereby a position of the second communication platform is determined by the determinable focusing of the communication connection.
According to another exemplary embodiment of the present invention, a method for determining the position of a communication platform is disclosed, comprising the steps of providing a communication connection between a first communication platform and a second communication platform, whereby at least the first communication platform can be in communication with the second communication platform, whereby the communication connection is formed as a focusable communication connection, determines the direction or orientation of the focusing of the communication connection, and determines a position of the second communication platform through the focusing of the determinable focusing of the communication connection.
The present invention describes a system and method for determining the position of a first communication platform by using another communication platform.
In the context of the present invention, the term communication platform should not be considered as limiting. Rather, depending on its role in the system and according to the invention, a communication platform should only needs to be able to provide an outgoing communication connection or be able to accept an incoming communication connection. The communication connection does not thereby have to be considered in a limiting sense, as in the case of a conventional data transmission connection, but may be able to transmit only identifiable information such as an of such a communication connection.
It is also conceivable that the communication connection according to the invention only provides information on the presence or absence of the communication connection. For example, by way of example with reference to a laser communication connection that extends from a communication platform and is detected by a further communication platform, for example by using a suitable photodiode, it may be sufficient for the inventive concept if the photodiode is capable of detecting the presence or absence of the laser beam, insofar as the communication connection itself is identified by other appropriate means. For example, in one application of the second communication platform, only a (determined) communication connection may occur so that simple determination without identification of the same may be sufficient.
Preferably, the communication connection has a defined form, such as a focusing. The communication connection is therefore not omnidirectional, but has a defined geometric shape or form. Again, for example, a laser beam would have a substantially one-dimensional embodiment in a near-field in the form of a one-dimensional line. If this laser beam is then detected, it gives at least the position of the communication platform detecting the laser beam that, along with the receiver, such as a suitable receiver diode, must be located in the longitudinal direction of the laser beam.
In the far-field, in turn, for example at a distance of more than 100 or 1000 km from the source of origin of the laser beam, the laser beam can, however, no longer be regarded as an idealized one-dimensional line, but has a substantially cone-shaped configuration with a cone radius that is dependent on the distance from the origin of the laser beam. Thus, the communication connection has a propagation volume, in which the communication connection can be detected. Thus, in the far-field there can be at least the case where such a laser is detected and where the receiver element is located at least in the propagation volume of the cone of the laser beam. However, it may be possible to verify with sufficient precision the exact geometry and the propagation volume of the communication connection using known mathematical methods.
One aspect of the present invention is therefore the detection of the presence of such a communication connection, which subsequently results in the knowledge that the receiver must be located at least in the propagation volume of this communication connection.
If the spatial propagation of the communication connection is now known with sufficient precision and based on the knowledge of the propagation, it is also possible to determine a position of the receiver element. Thus if for example, the position of a first communication platform, which is arranged as a transmitter for the communication connection, is deter with sufficient accuracy, while simultaneously the propagation direction and geometry of the communication connection are known, then the position of another communication platform, of a receiver communication platform, which is arranged in the propagation volume of the communication connection, can be deduced.
In this case, on the one hand, the information regarding the position, direction, orientation, and the propagation volume of the communication connection is transmitted via the communication connection, or can itself deduce its position from the presence of the signal via the receiving communication platform.
Thus, particularly preferred is a satellite-based location determination using a laser communication between a satellite, hence an apogee platform, and a near-earth returning platform, such as airplanes, drones, UAVs, vessels, balloons, etc. The ability to determine the location or to determine the direction of flight of the receiving communication platform is thus achieved in that a communication connection with a known propagation direction and propagation geometry or propagation volume, e.g. a laser beam, is detected, which communication connection is transmitted from a communication platform such as a satellite with a (high-precision) known position.
In this case the communication signal can itself provide a timing reference signal or flight time signal that can be compared with a time reference signal in the receiving communication platform, where appropriate, thereby simultaneously enabling the determination of the distance of the second communication platform from the first communication platform by determination of the elapsed time. Thus, starting from the known position of the first communication platform as well as the propagation geometry and propagation speed of the communication connection, it is also possible to determine the height of the second communication platform.
In addition, the inventive system based on a laser communication terminal installed on a satellite platform, as well as an aircraft serving as a receiving second communication platform, will be described. However, as previously stated, the exemplary embodiment of the communication platforms and the communication connection should not be considered as limiting.
The apogee satellite platform (efP) comprises a laser communication terminal, which is adapted to provide a communication connection to another communication platform using a laser beam. This communication platform can, for example, be arranged to be stationary on the earth's surface, whereby such a communication connection is substantially statically configured, or it can be associated with a mobile communication platform, whereby, due to the focused configuration of the communication connection, as well as the relative movement of the second communication platform with respect to the first communication platform, tracking of the communication connection oriented towards the second communication platform may be necessary.
In the case of the static embodiment of the communication connection, it may be sufficient fir a second communication platform, which, for example flies through the volume of the communication connection, to identify the communication connection. The mere presence of such a communication connection may also be sufficient, in particular by using firth information such as the geometric configuration of the stationary communication connection, to determine a position of the second communication platform in the propagation volume of the communication connection.
In the case of a variable aligned communication connection, for example in the case where the communication connection to the second communication platform is tracked, it can itself transmit more information with respect to the position of the first communication platform and/or the direction or orientation, or also with respect to the propagation volume of the communication connection, and provide this to the second communication platform.
The positioning of the second communication platform in the propagation volume of the communication connection now allows determination of the (own) position through the second communication platform, for example, based on the data received from the first data communication platform. Likewise, the first communication platform can directly transmit usable position information so that each communication platform that receives the information can determine the actual position due to the fact that it can receive the information.
Thus, a laser communication terminal can be used on a satellite platform not only for information transmission but also for determining the location of the receiver. Starting from a geostationary satellite and a conventional laser communication terminal, a laser beam generated on the earth's surface has a footprint with a diameter of about 1 km. An outstation for the satellite platform and thus a communication platform such as, for example, a near-earth returning platform, which can detect the laser beam, thus knows that it is located in the propagation volume of the communication connection between the satellite platform and the 1 km diameter footprint on the earth's surface. The extent to which the receiving, second platform is located at the center or at the edge of the propagation volume of a communication connection, can be detected, for example, by evaluating a reception power level. Using a known dynamic local scanning procedure, the position within the propagation volume, in particular the distance and the direction of an acquired propagation center axis, can likewise more accurately determine the position of the second communication platform in the propagation volume of the communication connection.
If, in addition, time alignment of the transmitted communication signal between the first communication platform and the second communication platform still takes place, then the distance between a first communication platform and second communication platform can be determined from the elapsed time as well as the propagation speed of the communication connection (normal speed of light). With this information, a three-dimensional position of the second communication platform in the propagation volume of the communication connection can be determined and thus, based on a high-precision known position of the first communication platform, the position of the second communication platform.
Position determination as previously described, in particular based on a laser communication terminal, may, in particular, for example, provide increased immunity to near-earth jammers of radio frequency signals from GPS or Galileo. Especially in the case of a laser method, this would only be interfered with by an object directly introduced into the laser beam between the first communication platform and a second communication platform.
The advantage with respect to magnetic-based or initial system-based localization methods is much higher accuracy as well as consistent positioning accuracy during a possible flight time, especially since no relative error needs to be added to an overall error.
Particularly advantageous is the additional use of several known position determination methods to provide a redundant position determination and, more particularly, to enable mutual position verification.
In addition, preferred embodiments of the inventive system for determining the position of a communication platform are described below.
According to a other preferred embodiment of this invention, the first communication platform may provide the direction or orientation of the focusing of the communication connection, the position of the first communication platform and/or the position of the second communication platform with respect to the second communication platform.
The second communication platform can subsequently determine a position in the propagation volume of the communication connection from this information.
According to another preferred embodiment of this invention, the first communication platform may be arranged to track the focused communication connection of the second communication platform.
Thus, the communication connection between the first communication platform and the second communication platform can be maintained independently of movement and position. Preferably, during tracking of the communication connection, the actual position or orientation of the geometric propagation volume of the communication connection can be transmitted to the second communication platform. This enables the actual position of the second communication platform to be determined through a continuous determination of the position of the second communication platform in the propagation volume of the communication connection.
According to a further preferred embodiment of this invention, the focusable communication connection may be in the form of a directional communication connection.
According to another preferred embodiment of this invention, information, in particular an elapsed time signal for the height determination of the second communication platform, may be transmitted via the communication connection.
This enables the distance between the first communication platform and the second communication platform to be determined, and thus the position of a spherical surface, whereby the first transmitting communication platform is arranged at the center of the sphere. By means of the formation of the intersection of the spherical surface with the geometric propagation or the propagation volume of the communication connection, the possible position of the second communication platform can be further restricted and determined more accurately.
According to another preferred embodiment of this invention, the communication connection may comprise an identification feature to uniquely identify the communication connection.
So, for example, a second communication platform, which (unexpectedly) receives a communication connection can determine the position by using the identification feature and, possibly, further information about the position or orientation of the communication connection belonging to this identification feature. This allows a flexible response to various independent communication connections implemented through the second communication platform.
According to another preferred embodiment of this invention, the direction or orientation of the focus of the communication connection and/or the position of the first communication platform can be identified or determined by the identification feature.
For example, the second communication platform, by querying a database, can identify information concerning the direction and orientation of the focusing of communication connection belonging to the identification feature, and can thus flexibly respond to an (unexpected) incoming communication connection, and determine its position.
According to another preferred embodiment of this invention, the second communication platform may be so arranged that it determines its own position on flying through a focused communication connection.
This may be particularly relevant when the communication connection is not a tracked connection of the second communication platform, but, for example, is connected to a stationary earth out-station or is aimed at defined points, for example, on the earth's surface. Thus, the geometric shape and propagation volume of the communication connection is, in essence, at least temporarily stationary, whereby the second communication platform can still determine its own position by means of the knowledge of the direction and orientation of the focusing of this communication connection. In addition, a communication platform can determine its own position by using a tracked communication connection of another communication platform along with information about the direction and orientation of the propagation volume of the communication connection.
According to another preferred embodiment of this invention, the communication connection may be formed as an optical communication connection, in particular as a laser communication connection.
According to another preferred embodiment of this invention, the first communication platform may be an apogee platform, especially a platform for operation outside the earth's atmosphere, more particularly a satellite, more particularly in a low-earth-orbit (LEO) or geostationary orbit (GEO) and/or the second communication platform may be a near-earth, returning platform, particularly a platform for operation in the earth's atmosphere, more particularly an aircraft, more particularly an airplane.
Further embodiments and advantages of the invention will become apparent from the following description. In various figures, identical or similar elements are provided with the same or similar reference signs.